Gas boiler having closed-type cistern tank

ABSTRACT

A gas boiler having a closed cistern tank with no diaphragm, in which the volume of the cistern tank can be reduced, the closed cistern tank storing returned heating water and absorbing pressure changes of the heating water. The cistern tank having no diaphragm has an internal space that is isolated from the atmosphere, and includes a heating water inlet through which the heating water is introduced, a heating water outlet through which the heating water is discharged toward a circulation pump, a water level detecting sensor which detects the water level of the heating water stored in the cistern tank, and a safety valve for maintaining the pressure of an internal space of the cistern tank to less than a predetermined value.

TECHNICAL FIELD

The present invention relates to a gas boiler having a closed-type cistern tank, and more specifically, to a gas boiler having a closed type cistern tank in which the capacity of the cistern tank is reduced and a separate air separator is not required.

BACKGROUND ART

In general, gas boilers are divided into atmospheric gas boilers and atmosphere cut-off type gas boilers.

FIG. 1 is a schematic view of a conventional atmospheric gas boiler.

The atmospheric gas boiler includes a circulation pump 10 which circulates heating water, a main heat exchanger 20 which transmits thermal energy of a burner 21 to the heating water forcibly delivered by the circulation pump 10, a three-way valve 30 which supplies the heating water to a heating pipeline (a place where heating is required) when a heating operation is performed, and supplies the heating water toward a hot-water heat exchanger 40 when hot water is used, the hot water exchanger 40 which supplies hot water by heating cold water, and a cistern tank 50 which stores returned heating water therein and absorbs a pressure change of the heating water. Reference numerals 61, 62, 63, and 64 represent a heating water supply pipe, a heating water returning pipe, a cold water pipe, and a hot water pipe, respectively.

The cistern tank 50 includes a water level detecting sensor 51 which detects whether or not the water level of the heating water is maintained in a determined water-level range, and an overflow pipe 52 through the heating water overflows to the outside when the water level of the heating water exceeds a predetermined value. Therefore, the heating water is opened to the atmosphere.

Such an atmospheric gas boiler has a simple structure and a low price. However, since the heating water circulation system is opened to the atmosphere, the boiler cannot be installed in a lower place than a heating pipeline (a place where heating is required). Therefore, the gas boiler has a positional limit. Further, since the heating water is exposed to the atmosphere such that oxygen is introduced, corrosion may occur in the heating pipe.

FIG. 2 is a schematic view of a conventional atmosphere cut-off type gas boiler. FIG. 3 is a schematic view showing a state before a closed type cistern tank is installed. FIG. 4 is a schematic view showing a case in which the maximum pressure is applied to the cistern tank of FIG. 3.

The atmosphere cut-off type gas boiler has almost the same structure as the atmospheric gas boiler in that a circulation pump 10, a main heat exchanger 20, a burner 21, a three-way valve 30, and a hot-water heat exchanger 40 are provided. However, the atmosphere cut-off type gas boiler is different from the atmospheric gas boiler in that a cistern tank 70 is constructed in a closed type so as to be isolated from the atmosphere, and an air separator 71, a safety valve 72, and a pressure gauge 73 are additionally installed.

The cistern tank 70 is a closed type tank which is isolated from the external air and includes a rubber plate 70 a, a gas storing unit 70 b, and a heating water storing unit 70 c. The rubber plate 70 a is interposed between the gas storing unit 70 b and the heating water storing unit 70 c. The gas storing unit 70 b stores gas (for example, nitrogen) therein, and the heating water storing unit 70 c stores heating water. The shape of the rubber plate 70 a is modified depending on applied pressure, thereby absorbing a pressure change of the heating water. The heating water storing unit 70 c is connected to a pipeline through which returned heating water passes.

Such an atmosphere cut-off type gas boiler has no limit in its installation position, and can prevent oxygen from being introduced into the heating water because the heating water circulation system is isolated from the atmosphere. On the other hand, it has a complex structure, and a high price. In particular, the air separator is necessary. Further, although the air separator is provided, it is difficult to remove the air from within the pipeline.

Further, when the pressure within the cistern tank is less than the atmospheric pressure, a vacuum may occur in the cistern tank. In this case, since the heating water cannot be circulated normally even when the circulation pump 10 is operated, the circulation pump 10 should be stopped, and water should be supplemented automatically or manually.

Further, in the atmosphere cut-off type gas boiler, the cistern tank is not effectively used. That is, as shown in FIG. 4, when the pressure of the heating water is maximized, the gas storing unit 70 b needs a space in which nitrogen is compressed. Since this space does not absorb the expanding heating water, it is an unnecessary space.

SUMMARY OF THE INVENTION

The present invention is directed to a gas boiler having a closed-type cistern tank with no diaphragm, in which the volume of the cistern tank can be reduced.

The present invention is also directed to a gas boiler having a closed-type cistern tank which can serve as an air separator, without a separate air separator.

The present invention is also directed to a gas boiler having a closed-type cistern tank, which can normally operate a circulation pump even when pressure lower than atmospheric pressure is applied to the cistern tank.

According to an aspect of the present invention, there is provided a gas boiler having a closed type cistern tank which stores returned heating water and absorbs a pressure change of the heating water. The cistern tank having no diaphragm is constructed in a closed type such that an internal space thereof is isolated from the atmosphere, and includes a heating water inlet through which the heating water is introduced, a heating water outlet through which the heating water is discharged toward a circulation pump, a water level detecting sensor which detects the water level of the heating water stored in the cistern tank, and a safety valve for maintaining the pressure of an internal space of the cistern tank to less than a predetermined value.

The safety valve may be installed on the uppermost end portion of the cistern tank so as to discharge the air before the heating water.

The cistern tank may be installed adjacent to an entrance of the circulation pump such that air separation is performed in the cistern tank.

The water level detecting sensor may be installed in such a manner that the lower end of the water level detecting sensor is adjacent to the bottom surface of the cistern tank.

When the water level detecting sensor judges that the water level is proper, the circulation pump may be normally operated even though the internal pressure of the cistern tank is less than atmospheric pressure.

According to the present invention, since the closed-type cistern tank has no diaphragm, the cistern tank can be easily manufactured, and the volume of the cistern tank can be reduced.

Further, even when the internal pressure of the cistern tank is less than atmospheric pressure, the boiler can be normally operated without stoppage.

Further, while the heating water circulation system is constructed in a closed type, the air separation can be performed smoothly, without a separate air separator installed.

DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic view of a conventional atmospheric gas boiler.

FIG. 2 is a schematic view of a conventional atmosphere cut-off type gas boiler.

FIG. 3 is a schematic view showing a state before a closed type cistern tank is installed.

FIG. 4 is a schematic view showing a case in which the maximum pressure is applied to the cistern tank of FIG. 3.

FIG. 5 is a schematic view of a gas boiler having a closed-type cistern tank according to the present invention.

FIG. 6 is diagrams showing cases in which the capacity of the cistern tank according to the present invention is sufficient in comparison with the water storage capacity of a heating pipeline.

FIG. 7 is diagrams showing cases in which the capacity of the cistern tank according to the present invention is not sufficient in comparison with the water storage capacity of a heating pipeline.

FIG. 8 is diagrams showing cases in which the capacity of the cistern tank according to the present invention is excessively smaller than the water storage capacity of a heating pipeline.

BEST MODE FOR INVENTION

Hereinafter, an example embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 5 is a schematic view of a gas boiler having a closed-type cistern tank according to the present invention.

The gas boiler according to the present invention includes a circulation pump 10 which circulates heating water, a main heat exchanger 20 which transmits thermal energy of a burner 21 to the heating water forcibly delivered by the circulation pump 10, a three-way valve 30 which supplies the heating water to a heating pipeline (a place where heating is required) when a heating operation is performed, and supplies the heating water toward a hot-water heat exchanger 40 when hot water is used, the hot water exchanger 40 which supplies hot water by heating cold water, a heating water supply pipe 61, a heating water returning pipe 62, a cold water pipe 63, and a hot water pipe 64, like the conventional gas boiler.

The gas boiler according to the present invention further includes a cistern tank 100. The cistern tank 100 having no diaphragm therein is constructed in a closed type such that heating water stored in the cistern tank 100 does not come in contact with the atmosphere. Therefore, the heating water circulation system is constructed in an atmosphere cut-off type.

A water level detecting sensor 110 is installed above the cistern tank 100. The water level detecting sensor 110 includes a short conductive body 110 a and a long conductive body 110 b, and measures resistance between the short and long conductive bodies 110 a and 110 b so as to judge whether or not a proper amount of heating water is stored in the cistern tank 100.

In this case, in order to sufficiently secure a space in which the air exists inside the cistern tank 100, the short and long conductive bodies 110 a and 110 b may be installed in such a manner that the lower ends thereof are adjacent to the bottom surface of the cistern tank 100.

In this example embodiment, the water level detecting sensor 110 is installed at an upper end portion of the cistern tank 100. However, the water level detecting sensor 110 may be installed on a lower portion of a side surface or a bottom surface of the cistern tank 100, with the length of the water level detecting sensor 110 being reduced, or may be installed in a connection pipe between the circulation pump 10 and the cistern tank 100 so as to be substituted with a sensor which detects whether or not heating water is present.

A safety valve 120 for maintaining the pressure of an internal space of the cistern tank 100 to less than a predetermined value is installed above the cistern tank 100. The safety valve 120 has a spring provided therein. When the pressure of the internal space of the cistern tank 100 exceeds the elastic force of the spring, the safety valve 120 is opened so as to discharge the air within the cistern tank 100 to the outside, thereby lowering the pressure.

In this case, the safety valve 120 may be installed on the uppermost end portion of the cistern tank 100 such that the air existing in the upper portion of the cistern tank 100 is discharged before the heating water stored in the cistern tank 100.

The cistern tank 100 has a heating-water inlet and outlet 100 a and 100 b formed in the bottom thereof. The heating-water inlet 110 a is connected to the heating water returning pipe 62 such that heating water can be introduced therethrough, and the heating water stored in the cistern tank 100 is discharged through the heating-water outlet 100 b toward the circulation pump 10.

Since the heating-water circulation system according to the present invention is constructed in an atmosphere cut-off type, the air introduced into the heating water needs to be separated. In this example embodiment, however, since the air separation is performed in the cistern tank 100, a separate air separator needs to be provided.

In this case, to prevent bubbles from being introduced into the circulation pump 10, the cistern tank 100 may be installed adjacent to an entrance 10 b of the circulation pump 10.

Hereinafter, operation of the gas boiler according to the present invention will be described.

Referring to FIG. 5, when the air is introduced into the cistern tank 100 while heating water circulates inside the heating pipeline, and if an amount of the introduced air is small, the air is absorbed into the upper internal space of the cistern tank 110. On the other hand, if an amount of the introduced air is large, the water level of the heating water within the cistern tank 100 decreases. Therefore, when the water level detecting sensor 110 judges that the water level of the heating water is lower than a proper water level, water is supplied through an automatic supplementary water valve (not shown).

As such, when the internal pressure of the cistern tank 100 is less than allowable pressure in a state where the water is supplied, the gas boiler operates as is. On the other hand, when the internal pressure of the cistern tank 100 is more than the allowable pressure, the safety valve 120 is operated so as to discharge the air to the outside.

FIG. 6 is diagrams showing cases in which the capacity of the cistern tank according to the present invention is sufficient in comparison with the water storage capacity of the heating pipeline.

FIG. 6A shows a case in which the temperature of the heating water decreases so that heating-water pressure is minimized, and FIG. 6B shows a case in which the temperature of the heating water increases so that the heating-water pressure is maximized. Therefore, only the water level within the cistern tank 100 changes depending on a change in the heating-water pressure, and the pressure within the cistern tank 100 is constantly maintained.

FIG. 7 is diagrams showing cases in which the capacity of the cistern tank according to the present invention is not sufficient in comparison with the water storage capacity of a heating pipeline.

FIG. 7A shows the cistern tank before the boiler is used after the boiler is installed for the first time. FIG. 7B shows a case in which, when the boiler is used for the first time, heating-water pressure is maximized by an increase in temperature of the heating water. FIG. 7C shows a case in which the temperature of the heating water decreases due to stoppage of a heating operation such that the heating-water pressure is minimized.

When the heating-water pressure is maximized as in FIG. 7B such that the pressure within the cistern tank 100 exceeds the allowable pressure, the safety valve 120 is opened so as to discharge the air to the outside, and the water level of the heating water significantly increases.

Thereafter, when the heating-water pressure is minimized as in FIG. 7C, the pressure within the cistern tank 100 may be less than the atmospheric pressure. Even in this case, if the water level detecting sensor 110 judges that the water level is proper, the boiler is normally operated.

FIG. 8 is diagrams showing cases in which the capacity of the cistern tank according to the present invention is excessively smaller than the water storage capacity of a heating pipeline.

FIG. 8A shows the cistern tank before the boiler is used after the boiler is installed for the first time. FIG. 8B shows a case in which, when the boiler is used for the first time, heating-water pressure is maximized by an increase in temperature of heating water. FIG. 8C shows a case in which the temperature of the heating water decreases due to stoppage of a heating operation such that the heating-water pressure is minimized. FIG. 8D shows a case in which water is supplemented through the automatic supplementary water valve from the state of FIG. 8C.

When the heating-water pressure approaches the maximum allowable value as in FIG. 8B, the cistern tank is filled up with the heating water, and an air layer disappears. In this state, when the heating-water pressure is minimized as in FIG. 8C, the water level decreases. Further, when the water level detecting sensor 120 judges that the heating water is insufficient, the automatic supplementary water valve is operated so as to supplement water. Thereafter, the above-described cycle is repeated.

As described above, the boiler according to the present invention can be normally operated regardless of the water storage capacity of the heating pipeline. Further, although the cistern tank having no diaphragm is used, the cistern tank can be constructed in a closed type. Therefore, a separate air separator does not need to be provided, and the capacity of the cistern tank can be reduced in comparison with the conventional cistern tank.

While few exemplary embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes may be made to these embodiments without departing from the spirit and scope of the invention as defined by the appended claims and their equivalents.

INDUSTRIAL APPLICABILITY

In the gas boiler having a closed type cistern tank according to the present invention, the capacity of the cistern tank can be reduced, and a separate air separator is not required. Therefore, the gas boiler has industrial applicability. 

1. A gas boiler having a closed cistern tank in which returned heating water is stored and which absorbs pressure changes of the heating water, wherein the cistern tank has no diaphragm has an internal space isolated from the atmosphere, and includes a heating water inlet through which the heating water is introduced, a heating water outlet through which the heating water is discharged toward a circulation pump, a water level detecting sensor which detects the water level of the heating water stored in the cistern tank, and a safety valve for maintaining the pressure of the internal space of the cistern tank at less than a predetermined value.
 2. The gas boiler according to claim 1, wherein the safety valve is located on an uppermost end portion of the cistern tank and discharges air before discharging the heating water.
 3. The gas boiler according to claim 1, wherein the cistern tank is located adjacent to an entrance of the circulation pump such that air separation is performed in the cistern tank.
 4. The gas boiler according to claim 1, wherein the water level detecting sensor is installed so that a lower end of the water level detecting sensor is adjacent to a bottom surface of the cistern tank.
 5. The gas boiler according to claim 1, wherein, when the water level detecting sensor detects that the water level is proper, the circulation pump is normally operated even when the internal pressure of the cistern tank is less than atmospheric pressure.
 6. The gas boiler according to claim 2, wherein the cistern tank is located adjacent to an entrance of the circulation pump such that air separation is performed in the cistern tank.
 7. The gas boiler according to claim 2, wherein the water level detecting sensor is installed so that a lower end of the water level detecting sensor is adjacent to a bottom surface of the cistern tank.
 8. The gas boiler according to claim 2, wherein, when the water level detecting sensor detects that the water level is proper, the circulation pump is normally operated even when the internal pressure of the cistern tank is less than atmospheric pressure. 